Prostate cancer treatment could double the chance of dementia

A common prostate cancer treatment that lowers testosterone could double the chances of men developing dementia, research suggests.

Androgen Deprivation Therapy (ADT) shuts down the body's main supply of the male hormone and is a less drastic alternative to physical castration.

It is a standard treatment for men whose cancers have started to spread and cannot be eliminated by surgery or radiotherapy alone.

But a new study suggests there may be a serious hidden danger associated with ADT - an increased risk of Alzheimer's and other forms of dementia.

'The risk is real, and depending on the prior dementia history of the patient, we may want to consider alternative treatment'

Scientists who analysed the health records of more than 9,000 patients found that when men were given ADT their chances of having dementia within five years doubled.

Prostate cancer treatment can involve hormone therapyCredit:
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In absolute terms, the risk is still small. Of the 1,829 patients who underwent androgen deprivation, just 7.9 per cent developed dementia.

This compared with 3.5 per cent of the group not treated with ADT.

Lead researcher Dr Nigam Shah, from Stanford University in the US, said: "The risk is real, and depending on the prior dementia history of the patient, we may want to consider alternative treatment."

'Men having treatment for prostate cancer are likely to be living with other health problems which may also increase their risk of dementia. No man should stop taking hormone therapy based on these findings'Dr Matthew Hobbs, Prostate Cancer UK

Around 47,000 men are diagnosed with prostate cancer each year in the UK, about half of whom are caught at an early stage before the disease has spread.

The study, published in the journal Jama Oncology, found that men aged 70 and older, and who had been on ADT for at least 12 months, were most at risk.

The most common form of ADT used in the UK is a drug called goserelin, sold under the brand name Zoladex, which is injected.

It interferes with signals from the brain that instruct the testicles to make testosterone.

The scientists urged prostate cancer patients receiving ADT not to change their treatment without consulting their doctors.

Prostate cancer is one of the most common forms of cancerCredit:
Alamy

Co-author Dr Kevin Nead, from the University of Pennsylvania, US, said: "I was surprised at how ubiquitous the effects on all types of dementia were, but I would definitely not alter clinical care based on our results."

He said more research was needed to look at the link between ADT and dementia and identify what kinds of patients might be most at risk.

Male hormones are known to play a role in the health and growth of neurons, which may help explain the association, said the scientists.

Another type of treatment blocks the action of testosterone on tumours rather than cutting off supplies of the hormone.

There is no suggestion that taking these drugs, known as anti-androgens, increases the risk of dementia.

Dr Matthew Hobbs, deputy director of research at the charity Prostate Cancer UK said: "Although this research suggests that there may be a link between hormone therapy and dementia, it's very hard to draw clear cut conclusions from studies like these and further research is needed to confirm the findings.

"Men having treatment for prostate cancer are likely to be living with other health problems which may also increase their risk of dementia. No man should stop taking hormone therapy based on these findings,” he said.

Dr Laura Phipps of Alzheimer’s Research UK, said: “This study is part of an active area of research into the role that sex hormones like testosterone could be playing in the brain in dementia. Studies like this, which take advantage of the rich data held in medical records, can be very useful for highlighting trends and potential risk factors for further research.

"While these results suggest a link between androgen deprivation therapy and an increased risk of dementia, they do not show that ADT is definitely causing this increased risk. We need to better understand the impact of sex hormones in the brain in diseases like Alzheimer’s to delve deeper into the possible reasons for this link."